Squatting often has a lot to do with your hip and glute strength, which is one of the reason why being sedentary often leads to lack of flexibility/mobility. Stuff like dead bugs, bird dogs, and alternating supermans are good to throw on top of squatting and other lower body work, especially if you have decent range of movement otherwise. Basically anything that gets your hips and butt engaged will very likely help alongside the stretching and squatting. A track suit can't hurt, either. You don't want your clothing to restrict your movement.